Terminal block construction



Dec. 29', 1.964 c, L. LI'NEBERGER 3,163,483

TERMINAL BLOCK CONSTRUCTION Filed Nov. 28, 1961 & l/II/I/L FIG. 3

II I I INVENTOR. III/l! I CLARENCE L. L/NEBERGER BY L/ AM ATTYS.

United States Patent 3,163,483 TERMINAL BLGCK CONSTRUCTION (Ilarence L. Lineberger, Chicago, Ill, assignor to Suttle Equipment Corporation, Chicago, 111., a corporation of Illinois Filed Nov. 28, 1961, Ser. No. 155,285 1 Claim. (Cl. 339-97) The present invention relates to terminal block cons'tructions and more particularly to a terminal block assembly for use in making electrical connections in telephone systems and the like.

It is an object of the invention to provide a terminal block assembly for use in making electrical connection to insulated lead wires without necessity for removing the insulation beforehand. It is another object of the present invention to provide a connection block assembly which enables greater reliability than conventional stripping techniques in that it avoids the risk of nicking the wire, and hence encouraging breakage, at the point of exit from the insulation. In this connection it is an object to provide a connection block assembly which produces a positive electrical connection with an insulated wire simply by screwing home a nut upon a stud and without any care or attention on the part of the user.

It is a related object to provide a connection block assembly for use with insulated leads and which not only results in a good electrical connection but which exhibits a mechanical strength many times that of conventional techniques with the lead Wire being resistant to hard jerks, repeated bending, and severe vibration. Moreover, it is an object to provide a connector block assembly which permits numerous reconnections without substantial weakening of the wire. Thus it is an object to provide a connector block assembly which is ideally suited to portable as well as fixed station use.

It is a further object of the present invention to provide a connector block assembly in which a plurality of insulated wires may be reliably connected to a common mounting stud.

It is a further object of the invention to provide a connection block assembly which is equally effective for the various types of insulation in common use in telephone practice, insuring penetration to the connector upon applying only the usual twisting or tightening force and without risk that the conductor will be severed or physically scraped by excessive tightening.

Other objects and advantages of the invention will become apparent upon reference to the accompanying detailed description and upon reference to the drawing in which:

FIGURE 1 shows a connection block assembly constructed in accordance with the present invention with the parts in exploded relation.

FIG. 2 shows a plurality of the assemblies anranged side by side on the connection block and with the lead wires tightened in position. I

FIG. 3 is a section taken through one of the assemblies of FIG. 2 and along the line 3-3 in the latter figure.

FIG. 4 is an enlarged fragmentary section taken along the line 4-4 in FIG. 3.

FIG. 5 shows the invention applied to an assembly capable of making connection to a plurality of lead wires on a single stud.

While the invention has been described in connection with a preferred embodiment, it will be understood that it is not limited to the particular embodiment but it is intended, on the contrary, to cover the various alternative and equivalent constructions included within the spirit and scope of the appended claims.

Turning now to the drawing there is disclosed in FIG. 1 a connection block assembly constructed in accordance with the present invention. This assembly includes a mount :or base in the form of a block of insulation 11 having a threaded stud 12 which may, if desired, be moulded in the base. Mounted at the lower end of the stud 12 is a nut 13 which is screwed tight and hence nonrotiatable with respect to the base. Arranged for threading on the stud 12 is a second nut 14, and interposed between the nuts is an insulated lead wire 15 having its end bent into the form of a hook.

In accordance with the present invention the lower nut 13 has formed on its upper surface a series of radially extending ridges 2.0, in the present instance six in number, which define insulation-penetrating edges, and the underside of the nut 14, which is screwed down upon the wire lead 15, is smoothly finished so as to permit slip page during the course of tightening thereby to insure that the lead wire remains in stationary position for acting upon by the penetrating ridges.

In a practical case and for standard telephone usage the stud 12 and the nuts 13, 14 may be of the size 10-32 although the invention may be applied to any size of connector. The ridges 20 are preferably integrally formed on the nut 13 and, in accordance with the invention, have a height which is somewhat less than the thickness of the insulation to be penetrated. In a preferred embodiment it is found that a height of 15 to 20 thousandths of an inch produces the desired penetration and making of contact with lead wires having a thickness of. insulation and wire on the order of 19 gauge to 26 gauge. Moreover, the ridges 20 preferably have sloping sides 21, 22 (see FIG. 4) defining an included angle on e order of defining an edge 23 which is well defined but nevertheless, because of the included angle, quite blunt. Such angle has been found to produce good penetration of plastic materials such as cellulose acetate, polyvinyl chloride, rubber, braided thread, enamel, and other commonly used soft insulation materials, and good electrical connection when the upper nut is screwed tight without danger of severing or nicking the conductor. However, it will be appreciated by one skilled in the art that the included angle, indicated at a, need not be precisely 90 and the angle may be made somewhat less than 90 to facilitatepenetration of tough plastic insulation and somewhat greater than 90 where the insulation has relatively poor penetration resistance. For a given type of special insulation and size of lead wire the angle may increase as necessary to avoid nicking the conductor or decreased as necessary to secure positive penetration. Experience has shown that a 90 angle is about optimum and that the angle should not, preferably, be varied more than, say, 25 from this value.

In general, ([llQCOlll'ltiCliOtI block 11 will have more than one of the connection block assemblies 10 and additional ones are indicated at Ma, ltlb and 100. In accordance with the usual telephone practice, two rows of studs may be provided with the total number running between six and twenty-six. If desired, the adjacent studs may be electrically connected together by integral jumpers as indicated at 25.

In practicing the invention it is desirable that only a single lead wire be secured between adjacent nuts. Where a plurality of connections are to be made to a given stud, a plurality of nuts are used on the same stud, with each of the nuts performing a dual function. Thus where four leads, indicated at 31-34, are to be accommodated, nuts 4144 are provided, in addition to the base.

nut '45, each of which has radial ridges formed in its top surface but with a smooth undersu-rface. In use, the lead wire 31 is hooked around the stud 46 and the nut 41 is screwed tight. This establishes electrical connection with the first wire. Next the lead wire 32 is hooked around the stud and the nut 42 screwed tight. This process is repeated for the wires 33, 34.

It is found that the connector block assembly described above not only makes it unnecessary for the electrician to scrape or otherwise strip the ends of the lead wires to be connected, with a substantial saving of time, but there are, in addition, a number of largely unforeseen practical advantages, characterized primarily by greatly increased reliability. As well appreciated by one skilled in the art, the mechanical stripping of the lead wires requires the use of a stripping tool or other sharp edged instrument, running the risk that the conductor itself may be nicked and seriously weakened at the point of exit from the insulation. This is a particularly critical region since, because of the sudden reduction in section, most of the bending stress is concentrated here whenever the lead wire is subjected to movement or vibration. In conventional practice the conductor itself is thin and has little mechanical strength, absent the insulation, so that stripping exposes the conductor to damage and breakage arising from a number of different sources. In addition to the breakage due to continued flexing, the conductor may be weakened and broken by overtightening of the clamping nut which tends to flatten the relatively soft copper conductor. In the present connection block assembly, not only is the strength of the insulation itself added to the strength of the conductor, but the insulation acts to provide a cushioning effect which protects the conductor and prevents any localized stress in the conductor except at the points of actual electrical connection. Finally, and most important, since there is no abrupt necking down of cross section any bending stress applied to the lead tends to be distributed over a length of the conductor rather than concentrated at one point.

With regard to reliability it may also be pointed out that by hooking the wire in the manner indicated the wire is acted upon by at least four to five of the ridges and consequently there are four to five points of electrical connection, any one of which will sufiice to provide adequate current carrying capacity.

While the invention has been described in connection with use of a nut for mounting the ridges which penetrate the insulation, nevertheless it will be apparent that the invention is not limited thereto but if desired the ridges may be formed on any metallic element at the base of the stud which is stationary with respect to the stud at the time that the penetration takes place.

The ridges may be formed in any convenient way, as, for example, by making the entire nut by a sintering 4 (molding) operation, use of dies, or by removal of metal using a suitable cutting tool. The use of sintering procedures, particularly for short runs, is preferred since this produces a relatively sharp and well defined penetrat ing edge.

The arrangement is ideally applicable wherever a high degree of mechanical strength and vibration resistance is required, in addition to good electrical conductants, and, if desired, the same lead may be connected and reconnected many times Without adversely aifecting its strength or integrity.

In the following claim the terms radial or radially extending as applied to the ridges applies to ridges which extend in a generally, though not necessarily precisely, radial direction. The term relatively smooth as applied to the finish on the underside of the nuts applies to any surface which is 'sufiiciently smoother than the ridged surface as to cause the lead wire to remain stationary at the ridged surface during the tightening operation.

I claim as my invention:

In a connection block assembly the combination comprising a base, a threaded stud mounted on said base, a plurality of nuts on said stud, each of said nuts having a top surface formed with radially extending ridges each having a well defined insulation-penetrating edge with the height of said ridges being slightly less than the thickness of the insulation to be penetrated, each of said nuts having a smooth under surface so that when an insulated lead wire is hooked around the stud above one of the nuts and acted upon by screwing down the nut above it, relative slippage takes place between the upper nut and the wire forcing the wire into insulation-penetrating engagement with at least four of the ridges for electrical and mechanical attachment of the wire to the stud.

References Cited by the Examiner UNITED STATES PATENTS 476,080 5/92 Sanche 399269 X 789,574 5/05 Steinberger 339198 964,741 7/10 Beghtol 339-99 1,336,736 4/20 Fenety 339-97 1,928,157 9/33 Levin 33997 2,078,825 4/37 Wisner 33997 X 2,525,123 10/50 Frank 339-97 2,562,032 7/51 Gutensohn 151-37 X 3,049,691 8/62 Cheney 339 JOSEPH D. SEERS, Primary Examiner. M. I-IENSON wooD, JR., Examiner. 

